Antenna for electric wave transmission



Dec. 4, 1928.

1,694,135 A. MEISSNER ANTENNA FOR ELECTRIC. WAVE TRANSMISSION Filed July15, 1925 Zlwwqntoc fllexand'erjyzsmer m W W $1M Patented Dec. 4, 1928.

UNITED STATES 1,694,135 PATENT OFFICE.

ALEXANDER MEISSNER, OF BERLIN, GERMANY, ASSIGNOR TO GESELLSCHAFT FURDRAHTLOSE TELEGRAPHIE M. B. H., OF BERLIN, GERMANY, A CORPORATION OFGERMANY.

ANTENNA FOB ELECTRIC WAVE TRANSMISSION.

Application filed July:15,1925, Serial No. 43,683, and in Germany July25, 1924.

An antenna for electric wave transmission through space often consistsof a high vertical aerial which is'caused to oscillate at such a wavelen th that the total length of the antenna is a out three-quarters ofthe length of the transmitting wave or else is the multiple of the wholewave length plus one-quarter of the same. Where the antenna oscillatesunder these conditions, the lower portion thereof which corresponds toabout one-' quarter of the wave length above the ground connection doesnot contribute any substantial portion of the total radiation from theantenna but, on the contrary, the energy issuing therefrom passes to theground, thereby resulting in ground losses.

The object of the present invention there- 'fore is to eliminate suchground losses. The

means which I provide to attain this object consists in surrounding thelower end of the antenna by a conductive body, preferably in the form ofa system of parallel vertical wires forming a screen of the type knownas the Faraday cage. This screen is connected with the source oftransmission so that the radiation which issues from the lower portionof the antenna is intercepted by the screen and is thereby'absorbed andrestored to the transmitting apparatus without substantial losses beingincurred.

Referrin to the accompanying drawing, the figure thereon illustrates theschematically preferred form of my invention. In accordance with thepresent invention, in this and the dotted line running from the point Athrough B to the base line at C illustrates the relation of the lengthof the transmitted wave to that of the antenna itself. The portion ABofthe antenna, as will be understood, is the part thereof which isintended to furnish the active radiation while the portion B-C isemployed for the exciting of the antenna as a whole. This portion,however, is the 0 portion which is substantially one-quarter of the wavelength that occasions the losses above mentioned. The series of verticallines indicated by R constitutes a reflecting screen preferably, asthere shown, consisting of a circular series of vertical conductingwires which are substantially equal in length to onequarter of the wavelength transmitted or substantially one-third of the height of theantenna. This conductive screen R is coufigure the line AC representsthe antenna,

pled' to the transmitting apparatus in any suitable way apparent tothose skilled in the art.

The illustration represents diagrammaticall the simplest manner in whichthis may be one, which is by coupling. The Vertical wires of the shieldR are grounded, as is the antenna. Since the wires are of the lengthspecified they are tuned, and constitute not merely a shield, but rathera series of tuned oscillators which are coupled to the lower part of theantenna. Because of the mutual coupling of the circuits the energyattempted to be radiated in the part BC of the antenna is induced backinto it again.' The action is much like that obtained with reflectingconductors, but differs from reflection in that the phase relations, andtherefore the spacing of the conductors from the antenna, is of nodirect consequence. Of course, the conductors R cannot be located tooremotely from the antenna because otherwise the energy will radiate, andwill not be recoverable efficiently.

It will therefore be apparent that since the conductive screen Rsurrounds the lower portion of the antenna, it will absorb the radiationfrom a corresponding portion of the antenna which radiation will then becoupled back to the source of transmission and reinforce the same sothat it will add to the energy transmitted from the upper or activeportion of the antenna;

It is to be understood that the aerial need not necessarily bethree-quarters of a wave in length, for my invention is applicable toany aerial which includes a useful radiating portion, and anotherportion not useful for radiation. r

In the claims which follow, I shall by the term electromagneticallycoupled mean that the coupling is by means of an electromagnetic wave.The energy transfer probably takes place by means of both the magneticand the electric components, but I do not wish to be restricted to thisrequirement, but merely wish to differentiate from a direct conductivecoupling, or a close magnetic coupling by means of transformer coils. Bythe term electrical length I mean the equivalent length if the conductorwere a simple linear one. Thus, if the conductor in question islengthened or shortened or tuned by any means, then the length is to beconsidered that length to which it is tuned.

What I claim and desire to protect by Letters Patent is: i

1. An antenna for electric wave transmission through space, comprisingan aerial conductor, and a conductive body located adjacent only thelower portion thereof and having' a height equal to substantiallyone-third of the height of said aerial, said conductive .body beingcoupled with the aerial to reinforce the energy transmitted therefrom.

2. An antenna for electric wave transmission through space, comprisingan aerial conductor, and a conductive screen surrounding only the lowerportion of the same, said screen being adapted to absorb the radiationfrom the adjacent lower portion of the aerial and reiinforce the energywhich is being transmitte 3. An antenna for electric wave transmissionthrough space, comprising an aerial conductor having a lengthsubstantially equal'to three-quarters of the wave length to be trans-v5. In combination, means to radiate a wave including an aerial whoselength is anodd number of quarter lengths of the wave, and a screen alesser odd number of quarter waves in length positioned closely to onlya portion of the aerial and energized thereb 6. In combination, means tor iate a wave including a grounded antenna whose length is anoddnumberofquarterlengths ofthewave and a grounded screen a lesser oddnumber of quarter waves in length placedadjacent to, and energized byenergy radiated from, only a portion of the antenna.

7. In combination, means to radiate a wave including an aerial whoselength is an odd number of quarter lengths of the wave, and a screen alesser number of quarter waves in length electromagnetically coupled toonly a portion of said aerial.

8. In combination, means to radiate a wave including an aerial whoselength is an odd number of quarter lengths of the wave, and a screen aquarter wave in length electromagnetically coupled to the lower portiononly of said aerial.

9. In combination, means to radiate a wave including an aerialwhoseelectrical length is an odd number of quarter lengths ofthe wave tobe radiated, and a radiation reventing screen, the total electricallength 0 which is a lesser number of quarter waves, coupled to saidaerial.

Signed at Berlin, Germany, this 23rd day of June, 1925.

ALEXANDER MEISSNER.

